1. Field of the Invention
This invention relates to a levelling device for ladders and the like.
2. Description of the Related Art
Difficulties have often been experienced in providing a firm and level foundation for a ladder when used on sloping or uneven ground. Various levelling devices which eliminate the need to support one leg of the ladder on blocks or packing pieces have been proposed. One such levelling device is disclosed in British Application No. 16660/48 (Hannington) published July 25, 1951. A serious disadvantage of this prior device, however, is that it cannot eliminate chatter of the friction locking devices when levelling initally. Hannington's friction devices can, and do, slip. Also because of its design, when weight is placed on the ladder, the arc is forced so far out of the plane of the ladder as to be dangerous to the user.
A more stable ladder levelling device is disclosed in my Canadian Letters Pat. No. 1,162,896, which issued on Feb. 28, 1984. The disadvantage of this device, however, is that it cannot be readily adapted for ladders of different widths.